New research suggests that the antibiotic cefazolin does not appear to help prevent surgical site infections following knee implant surgery.

In a study published last week in the Journal of the American Medical Association (JAMA), researchers from The Netherlands looked at whether a single preoperative dose of cefazolin actually helps prevent nee implant surgical site infections, after noting a high rate of infections following the use of devices used to treat fractures below the knee. However, the researchers found that the antibiotic provided few, if any, benefits.

Cefazolin has been on the market since 1971, and is used to treat a wide variety of infections. It is often considered a preferred drug for surgical prophylaxis, meaning that it is given to patients undergoing surgery to prevent possible infections. This study’s findings may bring that use into doubt.

Researchers note that following clean surgical procedures, the expected rate of surgical site infection should be less than two percent. However, infection rates following the removal of orthopedic implants for below-the-knee fractures has been reported to be more than six times that, as high as 12.2%.

In a randomized clinical trial involving 470 patients, researchers gave about half the patients a single, preoperative dose of 1,000 mg of cefazolin, and the other half a saline placebo injection from November 2014 through September 2016. They followed up with the patients over a period of six months.

According to the findings, 12.9% of the patients given cefazolin as a prophylactic still ended up with surgical site infections. That compares to just under 15% of the saline group; a difference the researchers said was insignificant.

“Among patients undergoing surgery for removal of orthopedic implants used for treatment of fractures below the knee, a single preoperative dose of intravenous cefazolin compared with saline did not reduce the risk of surgical site infection within 30 days following implant removal,” the researchers concluded.